Employing the Genesis IMMUNOSTRIP, a patented new and novel approach to immunoassay, we have demonstrated the feasibility of measuring serum digoxin. The availability of monoclonal antibodies against digoxin with proven association constants in the range of 1011 - 1012 M-1 will assure the required sensitivity, 500 pg/ml - 5ng/ml. This new assay system will benefit both patient and physician by providing important diagnostic information quickly (within 2 minutes), reliably and cost effectively. During Phase II we will develop production prototypes and explore detection systems which provide reliable data in a cost effective manner. Although the major focus of this project is on the rapid and reliable detection of serum digoxin, the IMMUNOSTRIP assay system has widespread applications for clinical laboratory diagnosis both in the hospital clinical laboratory and in the physician's office. In the latter case, it will not only permit the physician to deal quickly with dosages of toxic drugs but also to monitor drug compliance.